The present invention is directed to a method of clamping electrical contacts together for laser bonding the contacts and for improving the transfer of laser energy to the bond. In particular, the present invention is directed to an interlead bonding of a tape automated bonding (TAB) tape to an integrated circuit die.
One of the problems in laser bonding is holding the electrical contacts which are to be bonded together, properly aligned, and in proper contact to provide a good bond. U.S. Pat. No. 4,845,335 to Andrews et al. issued July 4, 1989 for Laser Bonding Apparatus and Method which discloses various mechanical structures and the use of a gas stream to hold first and second electrical contacts in engagement for bonding, as well as a method of bonding electrical leads to electrical bumps by providing the electrical leads with a coating that is coupled to the wavelength of the laser and has a lower melting point than the melting point of the leads or the bumps, and is hereby incorporated by reference.
The present invention is directed to various improvements in the method of clamping electrical contacts, both keeping the contacts in proper position and in proper engagement for laser bonding This becomes particularly important in bonding either in inner or outer electrical leads of a TAB tape. For example, bonding of TAB tape inner leads to an integrated circuit die, either having bumps or bumpless, is difficult because of the small sizes of the leads and bumps, if any, involved.